Telephone set



Nov. 21, 1939. A. MONTEL El AL 2,180,716

TELEPHONE SET Filed Aug. '7, 1936 2 Sheets-Sheet 1 AMONTEL M. RAB/NE BY Wm M ATTORNEY I INVENTORS Nov. 21, 1939. A. MONTEL ET A1.

TELEPHONE SET Filed Aug. 7, 1956 2 Sheets-Sheet 2 FIG. 2

' AMONTEL INVEMZSS'MRABINE 04m f. 7%

A TTORNEV Patented Nov. 21, 1939 UNITED STATES PATENT OFFICE 2,180,716 TELEPHONE SET Application August 7, 1936, Serial No. 94,720 In France October 3, 1935 3 Claims.

The present invention relates to improvements in telephone stations intended to be employed, for example, in mines containing fire-damp.

The invention provides in particular means for preventing the normal operation or partial or total dismantling of the station from causing explosions. In order to attain this object the invention provides means permitting the elimination of any risk of spark production in the members of the station.

According to another feature, the invention provides means for preventing the production of harmful sparks in the case of premature operation of the apparatus, for example in the case of partial dismantling or even when certain members are wrongly manipulated.

The invention and its various aspects and features will be understood better by means of the following description based on the attached drawings, in which- Fig. 1 shows a View in elevation of a subscribers station, one part of the lid or cover being shown broken in order to display the members inside.

Fig. 2 shows a side and sectional view of the telephone station of Fig. 1.

In Figs. 1 and 2 similar members will be designated by the same references.

A station is composed of two portions, the one, I, containing the members of the telephone station proper, and the other, 2, containing the feed batteries.

The portion l comprises the transmission and reception members and particularly two telephone receivers 3 and 4 shown in Fig. 1, and a fixed microphone 5 provided with improved means for preventing the production of sparks and of which a detailed description will be given later.

The station in particular is provided with a magneto 6 which can be driven through a tight joint by a crank l. The magneto is provided with a safety device against the production of inopportune sparks which will be described later.

The station also comprises a ringing mechanism shown with two outer bells 8 whose clapper 9 passes through a joint 10 and is actuated by an electromagnetic device II.

The station also comprises the ordinary members such as the inductance coil l2 with almost closed magnetic circuit, so as to permit in spite of its low volume approaching as near as possible to the perfect inductance coil only having low transmission losses. A light air-gap, however, is provided to maintain the impedance constant at all the acoustic frequencies.

The lid or cover is rendered gas-tight, for example, proof against fire-damp, by means of suitable joints such as fiat joints for the box containing the subscribers station and circular joints erected for the rotary axes, such as the axle l3 of the magneto, the axle M of the switchhook and the axle 9 of the bell clapper.

Devices are provided to eliminate any risk of the production of sparks and consequently of explosion of fire-damp when opening the lid of the station or of the feed-box or even when certain members such as the microphonic capsule for example, are dismantled.

A safety interrupter composed of the details l5, I6, I1, I8 and I9 is provided in the box of the station proper as well as the members 20, 2| and 22 in the feed-box. This interrupter functions in the following manner: as soon as the screw I9 or 2D is unscrewed, the plate I8 or 22 is released and the spring I! (the corresponding spring in the feed-box is not shown on the drawings) repulses the piston H5 or 23. The contacts of the groups of springs IE or 21 are thus opened and consequently the line and the microphonic circuit. Thus any risk of explosion of fire-damp is avoided which might be caused by a spark flying between the contacts of the switchhook or those of the magneto on account of an inopportune call. The microphone is also provided with a safety device shown in Fig. 2. The microphone capsule 5 is mounted on a spiral spring 24 under whose action the insulated contact 25 of the microphone is open and consequently the microphone circuit is cut on before the miorophonlc capsule is completely removed on account of the removal of the fixing screws such as 21.

The safety device of the magneto consists in. a metal plate 28 in one piece with the lid 29 and comprising an opening through which the crank 1 passes, thus rendering it impossible to remove the lid without first removing the crank of the magneto and thus preventing the latter from being actuated when the lid 29 is removed. Thus the danger of sparking by the contacts of the magneto when the box is opened is eliminated.

The device is provided in such a manner that the removal of the crank creates no aperture in the wall of the casing, the passage being obstructed by a sleeve 30 which is in one piece with the axle of rotation of the magneto and in which the crank is fixed.

What is claimed is:

1. A telephone set comprising a case having an open portion, a magneto and normally-closed circuit-controlling contact springs in said case, a cover for said open portion, and secured to said case, a crank member outside of said case for operating said magneto, said cover having an apertured off-set portion through which a portion of said crank member extends, said cover not being removable from said case unless said crank member is first removed, means on said cover memberfor maintaining said contact springs in normal condition until the cover is loosened or removed from the case, said cover containing a recess, a contact member in the bottom of said recess, a microphone unit in said recess having a contact member engaging said recess contact member, a mouthpiece plate member closing said recess for holding said unit in said recess, and means in said recess for disengaging said contact members when said plate member is removed.

2. A telephone set comprising a case, a microphone unit, a receiver, a magneto and normally closed circuit-controlling contact springs in said case, a removable cover member for said case, means on said cover member for maintaining said contact springs in normal condition until the cover is loosened or removed from the case, said cover containing a. recess, a contact member in the bottom of the recess, said microphone unit being positioned in said recess and having a con tact member engaging the recess contact member, a mouthpiece plate member closing said recess for holding said unit in said recess, and means in said recess for disengaging said contact members when the plate member is removed.

3. A telephone set comprising signaling devices including a magneto having a removable crank including a shaft portion, a housing for said devices having an open front and an orifice in a side wall thereof for the reception of said shaft portion, and a removable cover for seating on the housing over said open front and having a flange portion with an orifice therein registering with the orifice in the side Wall, said shaft portion snugly fitting both orifices, whereby disengagement and removal of said crank to render the magneto inoperative is necessary before the cover can be unseated from said housing.

ANDRE MONTEL. MENDEL RABINE. 

